integer llGetInventoryType(string name)
returns the type of the inventory value of name. If name is not in the object then INVENTORY_UNKNOWN is returned, otherwise it would return the appropriat INVENTORY_* flag. This would work well with the new INVENTORY_ALL flag as to allow for inventory types to be identified and handled without having to search for the type by brute force.
INVENTORY_UNKNOWN would be only for llGetInventoryType as a return type using it in any other llGetInventory* function would have no effect.